446 
CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY, 
Analyses  qfbentonite. 
1905. 
I. 
II. 
III. 
IV. 
V.           VI. 
VII. 
VIII.         IX. 
X.          XI. 
Crook 
Coun- 
ty. 
Natro- 
na 
Coun- 
ty. 
Weston 
Coun- 
ty. 
New- 
castle. 
Taylor. 
Lin- 
scott. 
CosgrilY. 
Cassa  Mining 
Co. 
Si02 
A1203 
Fe208 
MgO 
CaO 
Na20 
K2O 
G1.0S 
17.12 
3.17 
1.82 
2.  69 
.20 
65. 24 
15.88 
3.12 
I     5. 34 
63.  25 
17.62 
3.70 
(3.70 
I  4.12 
63.25 
12.63 
3. 70 
3.97 
4.12 
5^.78 
15. 10 
2.  40 
4.14 
.  i  3 
58.25 
24.  70 
2.  61 
1.30 
1.61 
1  ;(■,.;, 
23.9 
3.1 
1.0 
0.5 
64.0 
22.9 
3-.1 
2.0 
1.0 
64.0 
24.0 
3.2 
1.5 
.0 
60.18 
26.11 
!  - 
.80 
60.  lj 
26.  58 
|       1.01 
i      0. 23 
j       1.23 
S03 
.88 
9.17 
L.53 
1 .  58 
6.91 
H20 
*16.  26 
11.00 
5.0 
7.0 
6.7 
10.  26 
10.26 
Sp.  gr 
86.96 
98.75 
93.92 
2. 132 
C9.71 
98.41 
2.180 
97.47 
100.0 
100.0 
100.0 
99.89 
99.49 
I.  Analysis  by  Westfall. 
II,  III.  Analysis  by  W.  C.  Knight. 
IV.  Geologic  Atlas  U.  S..  folio  107  I  Newcastle). 
V.  Unknown. 
VI.  Analysis  by  II.  L.  Hodges. 
VII-IX.  Analysis  by  John  Ogden. 
X,  XI.  Analysis  by  Thomas  T.  Read. 
USES. 
The  shipment  of  bentonite  began  in  ISSN,  when  several  carloads  were  used  by  easleni 
firms  in  the  manufacture  of  hoof  packing,  a  dressing  or  poultice  for  the  inflamed  hoofs 
of  horses.  The  chief  use  of  the  clay  so  far,  however,  is  to  give  body  and  weight  in  the 
manufacture  of  paper,  and  practically  the  whole  output  of  the  clay  for  the  last  few  years 
has  been  taken  by  a  paper  mill  in  Denver,  Colo.  Other  uses  are  in  antiphlogistine,  a 
proprietary  remedial  dressing,  and  as  an  adulterant  in  candies  and  drugs.  Though  h'ghly 
plastic  it  is  unsuitable  for  the  manufacture  of  fire-clay  products  on  account  of  its  low 
fusibility.  It  could  possibly  be  used  in  the  manufacture  of  pottery  by  mixing  with  ground 
feldspar.  It  is  a  good  retarder  for  use  with  the  hard  cement  plasters.  Its  high  absorption 
of  glycerin,  as  compared  with  diatomaceous  earth,  suggests  its  substitution  for  the  latter 
in  the  manufacture  of  dynamite. 
GEOLOGIC   OCCURRENCE. 
The  bentonite  deposits  of  Wyoming  vary  somewhat  in  stratigraphic  pos:tion.  In  the 
vicinity  of  Newcastle  one  bed  occurs  near  the  top  of  the  Niobrara  formation,  and  another 
in  the  Graneros  shale,  the  basal  formation  of  the  Benton  group.  In  the  Bighorn  basin 
the  deposits  also  occur  in  the  Graneros,  a  short  distance  below  the  Mowry  submember 
of  that  formation.  In  the  Laramie  basin  the  bentonite  beds  are  also  in  that  portion 
of  the  Benton  corresponding  to  the  Graneros,  but  they  lie  a  short  d'stance  above  the 
Mowry  beds.  Just  above  the  deposits  :s  a  bed  of  very  black  shale  and  in  th's,  at  a  distance 
of  15  or  20  feet  from  the  bentonite,  are  many  highly  ferruginous  septaria.  The  thickness 
of  the  bentonite  in  the  Laramie  Basin  ranges  up  to  4  or  5  feet,  but  in  the  Bighorn  Basin 
there  are  beds  over  7  feet  in  thickness  and  near  Newcastle  one  is  reported  to  have  a  thick- 
ness of  12  feet. 
LARAMIE  BASIN   DEPOSITS. 
Taylor's.— This  pit  was  opened  in  1888  in  the  NW.  J  SE.  J  sec  30,  T.  22  N.,  R.  75  W. 
about  one-fourth  mile  north  of  Rock  Creek  station,  on  the  original  line  of  the  Union  Pacific 
Railroad,  now  abandoned.     The  clay  crops  out  here  on  the  slope  of  the  hillside,  with 
